1. Field of the Invention
The present invention relates to an electric connector, and more particularly, to a movable connector including a movable housing.
2. Description of the Related Art
A bottom entry connector is known as a connector that conductively connects a connection object to a circuit on a substrate. In this connector, a connection object, for example, pin terminals of a pin header are conductively connected by being inserted into a housing from a back surface opposite from a mounting surface of a substrate. The substrate has through holes through which the pin terminals are to be inserted. In such a bottom entry connector, since the insertion holes for the pin terminals are open in the bottom surface of the housing, the housing is accurately mounted at a predetermined position on the substrate. If the center axes of the insertion holes and the pin terminals are not aligned, it is difficult to smoothly insert the pin terminals. If the pin terminals are forcibly inserted, load is applied to contact portions of the terminals and soldered portions connected to the substrate.
Accordingly, it is known that a bottom entry connector is formed by a movable connector (see, for example, Japanese Unexamined Patent Application Publication No. 2014-165066). This bottom entry connector includes a fixed housing to be disposed on a mounting surface of a substrate, and the fixed housing has a receiving part opening toward through holes in the substrate to receive a movable housing. In the receiving part, the movable housing is disposed in a floating state with a gap between the movable housing and an inner wall that defines the receiving part. The movable housing is displaceably supported by spring portions of terminals fixed to both the fixed housing and the movable housing. When the center axes of insertion holes of the movable housing and pin terminals are not aligned, the movable housing receives the insertion force of the pin terminals, and is displaced by the soft spring portions to remove misalignment between the center axes. Thus, it is possible to smoothly insert the pin terminals and to reduce the load applied to contact portions and soldered portions of the terminals.
In the movable connector including the movable housing, a stopper structure for stopping excessive displacement of the movable housing is generally provided, for example, to protect the terminals. Such a stopper structure is formed by a contact structure between the movable housing and the fixed housing, and is composed of, for example, abutment projections projecting sideward from side walls of the movable housing in the longitudinal direction and abutment receiving portions provided inside the fixed housing.
When a connection object is inserted in such a movable housing, the movable housing receives the insertion force of the connection object, and is thereby displaced until the abutment projections abut on the abutment receiving portions. Even after the abutment projections abut on the abutment receiving portions, insertion of the connection object is continued until the connection object reaches a predetermined fitting position. At this time, the movable housing continues to receive the insertion force of the connection object by the abutment projections at both ends, and a longitudinal center portion of the movable housing is curved and deformed to project in an arcuate form in the inserting and fitting direction of the connection object. Then, in the terminals at the center portion of the movable housing, spring portions are slightly stretched from the beginning of fitting, and load is constantly applied thereto. Hence, fatigue durability becomes lower than the designed value. If the movable housing to be displaced by, for example, vibration continues to be elastically supported in this state, the spring portions may be broken. This deteriorates connection reliability.
When the movable housing is curved and deformed in the arcuate form, as described above, the fitting length by which the connection object is fitted to the terminals becomes short in the center portion of the movable housing. Hence, the designed fitting length is not obtained, and this may also deteriorate connection reliability.